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Oct. 19, 2011 -- About 11% of Americans aged 12 or older take antidepressants, including many who have not seen a mental health professional in the past year, according to a new federal report.

The report by the CDC's National Center for Health Statistics also says that the rate of antidepressant use in the U.S. has increased nearly 400% since 1988.

Who Uses Antidepressants

Among key findings in the study:

Antidepressant medication was the third most common prescription drug taken by Americans of all ages from 2005 to 2008.

Antidepressants were most frequently used in that time period by people between 18 and 44.

Most people who take antidepressants do so to treat depression, but the drugs also are used for other disorders, such as anxiety.

Females are more likely to take antidepressants than are males, whites are more likely to take the medications than are African-Americans, and African-Americans are more likely to take the drugs than are Mexican-Americans. Overall, about 40% of females and 20% of males with severe depressive symptoms take antidepressants.

More than 60% of Americans on antidepressants have taken the drugs for two or more years, with about 14% taking the medication for a decade or more.

Less than a third of people taking one antidepressant drug have visited a mental health professional in the past year. Less than a half of those taking multiple antidepressant medications have seen a mental health professional in the past year.

About 8% of people aged 12 and over who had no current depressive symptoms took antidepressant drugs.

Antidepressant Use by Gender and Age

More than a third of females and less than a fifth of males with moderate symptoms of depression take medications to treat their mood problems, according to the report.

Females are 2.5 times more likely than males to take antidepressants, but there is no difference by sex in rates of use of antidepressants among people between 12 and 17.

The study shows that 23% of women between 40 and 59 take antidepressants, more than in any other age-sex group. Males and females aged 40 and over are more likely than younger people to take antidepressants.

The researchers say it is important for people who have depressive symptoms to be treated, and emphasis needs to be placed on increasing treatment rates among adults and children.